code: def test_all_cat_None_1(df):
      """
      Test output where a string is provided.
      """
      result = df.encode_categorical(names="sort")
      categories = pd.CategoricalDtype(
          categories=df.names.factorize(sort=True)[-1], ordered=True
      )
      expected = df.astype({"names": categories})
      assert expected["names"].equals(result["names"])
  
imports: import datetime
  import numpy
  import pandas
  import pytest
  from hypothesis import given, settings
  from pandas.testing import assert_frame_equal
  from janitor.testing_utils.strategies import categoricaldf_strategy, df_strategy
label_desc: Use image node_id 21 for calling a global function with example usage: test_all_cat_None_1(df) without return types